A headphone amplifier is a piece of equipment that is required to monitor the signal of line-level audio devices. A headline amplifier may have multiple amplified headphone outputs, making it a popular tool for production studios, broadcast vehicles, and major networks. Headphone amplifiers allow users to boost headphone volume with little or no distortion, which is a very important feature when working on stage or in loud recording environments. ProAudio.com showcases the best headphone amplifiers in the business from best-in-class brands.